Evaluatingthe genetic parameters for some morpho-physiological traits in wheat using diallel analysis

To assessthe genetic parameters of morpho-physiological traits in wheat, six bread wheat genotypes and their partial diallel progenies were evaluated in a randomized complete block design with three replications at GachsaranAgricultural Research Station, Gachsaran, Iran,in 2013-14 cropping season. Regression coefficient indicated there were not the assumptions of additive-dominance model for number of days to flowering and maturity, plant height, spike length, 1000-grain weight and extrusion length of spike from flag leaf. Both dditive and non-additive gene effects played an important role in controlling the seedlinggrowth vigor, grain-filling period, chlorophyll content, canopy temperature, grain length and grain yield, but the role of non-additive was superior the additivegene effects. The average degree of dominance were 1.02, 1.05, 1.32, 1.41, 1.39 and 1.62 for above mentioned traits, respectively, which showed the role of over-dominance gene action in their controles. The results of Hayman’s graphical analysis indicated that increasingseedling growth vigor, grain yield, grain length and canopy temperature by recessive alleles and chlorophyll content by dominant alleles were controlled. The role of non-additive and over-dominance gene action in controlling grain yield showed the possibility of using the heterosis to improve this important trait in new wheat varieties. The hybridsKouhdasht × (DAMARA-6 ICW99-0427-8AP-0AP-0AP-3AP-0AP) and Kouhdasht × (PASTOR/2*SITTA// PBW343*2/KUKUNA) due to the high heterosis and also the highest grain yield among the all studied genotypes in this research,it is recommended to use heterosis phenomenon for increasing grain yield in wheat breeding programs.